I don’t usually take electrolytes unless its over 4 days so merely take this as my opinion and completely useless input– but in my opinion Id say stevia probably isn’t the best to be taking during a fast regardless of breaking it or not, can imaging it being quite harsh on your stomach, esp since id imagine there’s other chemicals in those flavoured supplements? those really are usually designed to be taken with food, not for an empty stomach since the stomach is quite sensitive. You probably don’t need to be having electrolytes as frequently, a couple/few times a day should be enough and just regular water through the day, which would make the taste more tolerable for you if its an occasional thing and not your constant drink, or take it stronger and more as a shot.
personally I use “Electrolyte Powder” from Bulk which is 100% just the ingredients themselves, no extras, and take a shot of it a couple times a day, never had issues so far. Yes its salty, but its over with quick and I don’t need to worry about it for most of the day. (having it in warm water also helps me get it down easier)